The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the electronics industry utilized various methods and structures to form switching power supply controllers that were used to regulate the value of an output voltage. In some applications, the power supply controller used the value of the current through a power switch of the power supply system in order to assist in regulating the value the output voltage. In some operating modes, for example the continuous conduction mode, it was desirable to modify the value of the current sense signal in order to prevent sub-harmonic oscillation in the output voltage. This technique was often referred to as providing current sense ramp compensation. One example of a circuit that provided such current sense ramp compensation was disclosed in the data sheets for devices referred to as the NAP1217 and NAP1230 that were available from ON Semiconductor of Phoenix, Ariz. The prior compensation was difficult to integrate onto a semiconductor die together with a power switching device.
Accordingly, it is desirable to have a method of providing current sense ramp compensation that is integrateable onto a semiconductor die together with a power switching device and a method of providing adjustable current sense ramp compensation that is integrateable onto a semiconductor die together with a power switching device.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. Also, bipolar devices may be used instead of MOS devices. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.